To tell if your power supply is bad, first conduct a jump start test. It will show you if the power supply actually turns on. This is only a basic test, though.
To thoroughly verify if your PSU is bad, perform a multimeter test as well. Grab a multimeter and measure the voltage in each of your ATX power connector’s 24 pins.
If the measured voltage lies beyond the expected voltage range, your PSU is defective. Let’s get into the details.
Signs Of a Faulty PSU
Before getting to the actual procedure, here are some basic signs and symptoms that will help you determine if your PSU is failing.
- Your PC won’t turn on
- PSU keeps restarting
- You hear a clicking/buzzing sound from PSU
- PSU overheats
- You feel electric shocks while touching it
- Burning smell from PSU
- You feel like something is moving while shaking the PSU. Stuff like screws or anything burnt might move inside the chassis
These signs usually aren’t enough to make a conclusive diagnosis. But if you notice them, it does mean that a proper PSU test is due. Begin with a jumpstart test, then proceed to the multimeter test.
Conduct a Jump Start Test
Alright! Here’s how to check your PSU health with a jump start test. You can follow the same steps for testing all the PSUs these days since they have a standardized ATX pinout.
- Turn off your PSU and get it out of the PC case. Grab the 24-pin ATX power connector and hold it this way. The notch should lie on the right side.
- Jumpstart the PSU. For this, take a piece of metal wire (preferably a paper clip). And use it to short the PS_ON# pin (no. 16) and GND pin (no. 15 or 17). Keep the clip/wire attached to these pins. Make sure it is not loose.
- Turn your PSU on. The power supply should turn on and fans must rotate. Should the fans not spin, you have a bad power supply.
Please be mindful that the fans might spin for a while and come to a halt after a few seconds. This happens because your PSU has a zero-RPM or hybrid fan mode.
So, don’t yet conclude that your PSU is bad. Use a multimeter and conduct a digital multimeter test (DMM) before that. In fact, I advise you to conduct the DMM test whether or not the fans spin.
Test Your PSU Using a Multimeter
The multimeter test will help you know if every pin on the 24-pin power connector supplies the correct voltage to your PC.
To conduct this test, bring a multimeter and set it to measure DC voltage. Keep the clip/wire attached to the connector and check the readings on each of the 24 pins.
For example, you should get anywhere between +3.135V and +3.465V while testing a +3.3V pin. Similarly, it is between +11.40V and +12.60V for a +12V pin.
The voltage should always lie between the tolerance limits. No discrepancies are bearable.
For detailed instructions, view our guide on safely testing a PSU.
If the PSU neither passed the jump test nor the DMM test, you can conclude your PSU is faulty.
Lightbulb Moment:
On my system with EVGA SuperNova 650 G3 PSU and mini-ITX motherboard ASRock Fatal1ty AB350 Gaming-ITX/ac, the power supply did not turn on when connected to the system. But it worked like a charm out of the PC case. It passed both the paperclip and DMM tests as well.Later, I found that my motherboard had a short circuit. To protect itself from damage, the PSU triggered the OverCurrentProtection feature and refused to turn it on.
What I basically mean here is, a bad motherboard can also cause a functional PSU to seem bad. So, don’t jump to a conclusion until you conduct independent tests to check the well-being of the PSU and motherboard.
Test Your Motherboard
Alright! Now that you have tested your power supply and found the PSU to be fine, test your motherboard as well.
For that, reconnect the PSU to your system and turn it on. Start by checking if there are any orange LEDs or Debug LED/HEX codes glowing on the motherboard. Also, listen for any beep codes.
Additionally, try turning on your computer from the motherboard by shorting the PW+ and PW- pins on the front panel header. If shorting the pins turns your PC on, you probably have a bad front panel connector or the motherboard header.
While at it, also scrutinize your motherboard for any burnt parts. Carefully inspect if it has any bulged/cracked or leaking capacitors. Also, check if any onboard chips are broken.
Similarly, look for bent/broken CPU pins and motherboard headers. Examine visible damages too.
If either of the above-discussed cases holds true, your motherboard is probably defective/dead.
Do note that testing/repairing the motherboard is a sophisticated process and needs extensive hardware knowledge. So, I recommend taking it to your vendor/repair center for further troubleshooting.
If you prefer doing it on your own, refer to our detailed guide on testing a motherboard.